24 HOLMES. 



flask tightly corked, shaken, and allowed to stand for one-half hour. The 



1ST 

 uncombined bisulphite is then determined by titration with ^ iodine solution 



and starch indicator. Blank determinations are made in the same manner. 



The calculation of the aldehyde as acetaldehyde is made according to the 

 formula. 



cc. — iodine solution used up X 550.7 



Grams acetaldehyd-* per 100 liters proof spirits = 



per cent alcohol in sample. 



The Allen-Marquardt procedure for the determination of fusel oil 

 as given in the methods of analysis of the Association of Official Agri- 

 cultural Chemists 2 has been modified in several particulars. Preliminary 

 experiments with known amounts of amyl alcohol indicated that the 

 method gave only about 80 per cent of the amyl alcohol present; a 

 degree of efficiency corresponding very nearly to that reported by C. A. 

 Crampton. 3 This discrepancy is due in a large measure to the erroneous 

 assumption that inorganic acids are present in the distillate obtained 

 after oxidation, which must be first neutralized by titration, employing 

 methyl orange as indicator. 



Mann and Stacy * have shown that no inorganic acid is present in 

 this distillate and that the acidity indicated by methyl orange is organic. 

 In our method, the final distillation is made with steam, care being 

 taken not to reduce to any great extent the volume of liquid in the 

 distilling flask. About 300 cubic centimeters of distillate are collected, 

 titrated with phenolphthale'in and the entire acidity considered as valeric 

 acid. 



About twenty of these distillates were carefully tested for inorganic acidity 

 with negative results. No hydrochloric acid was found even when the final washing 

 of the carbon tetrachloride extract with saturated sodium sulphate was omitted. 

 It seems probable that there is some loss of valeric acid during the oxidation, 

 although the evidence in the literature upon this question is contradictory. 5 On 

 the other hand, Mann and Stacy demonstrated that with temperatures above 

 15.° 6 the separation of ethyl alcohol and amyl alcohol is incomplete and that 

 an appreciable amount of ethyl alcohol is left in the carbon tetrachloride, and a 

 corresponding amount of acetic acid found in the final distillate. Since the 

 temperature of this laboratory varies very little from 30° it is probable that the 

 positive error thus introduced more than compensates for any loss of acid. 



Mann and Stacy ° have devised a further modification of the method by substitu- 

 tuting for the eight hours' oxidation with reflux condensers, on oxidation of four 

 hours or even less in mechanically shaken pressure bottles, thereby effecting an 

 economy in time and eliminating the possibility of loss of valeric acid. 



2 U. 8. Dept. Agric. Bur. Ghent. Bui. 107 (1908), 98. 



'Proced. 23d Ann. Convention of Association Off. Agr. Chem. Bui. 105, 

 Bureau of Chem., U. S. Dept. Agr. (1907), 20. 

 f Joum. Soc. Chem. Ind. (1906), 25, 1125. 



5 Schidrowitz, Analyst (1901), 31, 181; Loomis, loc. cit. Bull. 105. 22. 

 * Loc. cit. 



